Monitoring the condition of gearboxes, motors, transmissions and other electrical and/or mechanical components comprising parts which rotates during use are well known. Particularly wind turbine gearboxes used in remote installations, such as in an off-shore wind turbine operating without permanent supervision, vibration monitoring techniques have proven very efficient for detecting problems at an early stage, hereby making it possible to initiate preventive maintenance or repair before any major damage occurs.
Epicyclic gears are properly the most compact embodiment of a gearbox, and in applications, such as wind turbines, where minimum size and weight are important, the use of epicyclic gearboxes is very widespread. But epicyclic gears have the major downside that smithereens from small initial damage may be torn through the gear contacts and bearings and thereby cause severe secondary damage.
In worst case, smithereens may cause the entire gearbox to seize, causing heavy damage not only to the gearbox itself but also to the equipment providing the input and the equipment receiving the output from the gearbox.
It is therefore known to provide the gearbox housing with one or more accelerometers or microphones for monitoring the condition of the gears and bearings. The output from these sensors is then filtered, using more or less complex methods, in order to be able to identify damage or potentially destructive conditions.
But in gearboxes such as epicyclic gearboxes, where rotating parts rotate on other rotating parts, the relatively small vibrations amplitudes of initial damage can easily be modulated e.g. by heavy gear impacts, hereby making it very difficult to pick up or identify the significant frequencies.
An object of the invention is therefore to provide for a technique for improving the detection of both initial and secondary damage in wind turbine gearboxes.
Furthermore, it is an object of the invention to provide for a technique for improving the detection of both initial and secondary damage in epicyclic gearboxes.